Feedback Solenoid

Fig. 2 YFA carburetor W/feedback solenoid:

YFA Carburetor
This solenoid assembly, Fig. 2, is an integral part of the carburetor. The feedback solenoid operates as a pulse width modulated (dithering) solenoid, varying the air bled into the idle and main metering circuits. In response to commands from the MCU or EEC system, the solenoid will vary the air/fuel ratio delivered into the engine.